Keeps crashing

 I have reinstalled minecraft like 3 times. Everything is up to date, and I have reset my pc twice. The progress bar goes to about 95% of the way, then stops moving, and sits there until the screen is clicked on. Then it goes white and says not responding, till I click on it more. Then it says java null reference exception or whatever ect ect and gives me the options to wait or close the program.  If I wait nothing happens, but if i terminate it it closes and pulls up the "You crashed" thing. There are no crash logs, and I also noticed there is no config folder. What should I do? It was working fine till i tried installing optifine. Then even after I reinstalled, it screwed up.